1. Field of the Invention
The present invention relates to shoe sole and heel constructions and, in particular, to such constructions with fluid-filled cavities for providing cushioning and forward thrust.
2. Description of the Prior Art
Various types of shoe sole and heel constructions having fluid-containing cavities have heretofore been provided, such constructions being disclosed, for example, in U.S. Pat. Nos. 5,678,328, 5,545,463 and 5,524,364. The present invention is an improvement of a construction disclosed in U.S. Pat. Nos. 5,678,328 and 5,545,463 which includes fluid-containing chambers or compartments which are formed, at least in part, by cavities in a midsole hermetically sealed to an outsole. Each midsole cavity may cooperate with a like outsole cavity to form the associated chamber. While such arrangements generally work well in terms of cushioning the user's foot and providing forward thrust during walking, the midsole cavities may cause discomfort to a user's foot, particularly in the case of relatively thin midsoles. Furthermore, the pressure exerted on the fluid-filled chambers by a user's foot in normal use can create regions of localized very high pressure, at least momentarily, which can cause some leakage of fluid, either from the seams between the midsole and the outsole members or through the midsole itself, which is generally formed of a somewhat porous material and, as was indicated above, may be relatively thin.